The current mindset today in the upstream oil and gas industry is that unconventional reservoirs, such as shales, need to be hydraulically fractured to produce gas and oil because they are “tight”. If that premise is true, then why were shale reservoirs, such as the Monterey in California, the Pierre in Colorado, and the Marcellus in New York, so productive in the early 1900’s – long before hydraulic fracturing was ever invented?
The answer is simple. They were drilled without overbalanced mud systems, and even though they were only vertical wells, they still were able to encounter a cross section of the formation’s natural fracture system and access significant oil and gas resources.
Many early Monterey Shale wells exceeded 10,000 BOPD without fracking – impossible if shales are too tight to produce without fracking. When most industry professionals talk about a shale reservoir being tight, they are generally referring to the matrix which is a correct observation. What is not considered is the permeability contribution from natural micro and macro fractures that exists in all hard (brittle) sedimentary rocks such as shales. Determination of the “collective” permeability system is important to understanding why so-called tight rocks have adequate permeability to produce naturally without being hydraulically fractured. It is important to remember that a single natural fracture with an aperture of only 25 microns will have over 50 Darcies of permeability. Nearly all industry experts agree that natural fractures are a critical key to the success of shale reservoirs. If this is true, then why do we plug them up and damage these natural fractures with mud and cement?
One reason that the natural fracture system in the rock is often ignored is because everyone knows the near wellbore region penetrated by a horizontal wellbore will be plugged up with drilling mud and rendered impermeable. First and foremost, the job of a mud engineer is to actually inflict maximum permeability damage upon the near wellbore region so that no hydrocarbons whatsoever enter the well during drilling to control pressure. However, the time has come to drill the horizontal wellbore in a different way, with new technology, that allows producers to focus on protecting the productive formation while being drilled and using existing down-hole technology to determine when to switch from conventional drilling methods – that destroy the near wellbore permeability – to a more near balanced drilling technique that protects intrinsic reservoir characteristics. The rewards for preventing formation damage while drilling the horizontal lateral include increased productivity and the elimination of hydraulic fracturing. The reward for eliminating hydraulic fracturing is cutting total well development costs in half.
With the industry focused on maximizing profitability from unconventional reservoirs, a new methodology of non-damaging reservoir drilling is needed to eliminate formation damage. It is no longer good enough to just prevent plugging from overbalanced mud systems because there are several other damage mechanisms inherent to poor quality reservoirs, such as shale. Fines migration and clay swelling are other documented damage mechanisms in shales that need to be eliminated. The damage occurs because many shales have high clay mineral content (>25%).
What if the technology was available to drill horizontally without causing any formation damage to the near wellbore region? Don’t you think it would be worth trying? Given the oil and gas industry’s current situation there needs to be a paradigm shift as to how we drill the reservoir to increase productivity and reduce costs. If we don’t come up with a better way we may not survive. Albert Einstein once said the definition of insanity is doing the same thing over and over again and expecting different results.
A new drilling process called “Near Balanced Reservoir Drilling” (“NBRD”) is being developed to gain entry into sub-surface rock formations without damaging the extensive natural fractures and exceptional permeability of the resource formation. In simple terms, the NBRD approach protects the targeted rock formation during drilling by taking a “surgical” approach to drilling so other completion processes, such as hydraulic fracturing, are not required to repair the damage to a formation caused by traditional drilling methods. This allows the intrinsic rock properties to naturally produce energy resources without hydraulic fracturing.
For more information about Near Balanced Reservoir Drilling, please contact Dan Genovese at dgenovese@enercominc.com.
Dan Genovese is a Director at the energy consulting firm EnerCom, Inc. with experience in corporate strategy, investor relations, ESG, government relations and policy. Mr. Genovese has worked in capital markets and has experience in upstream production and downstream energy demand.
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